Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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810 FXUS62 KRAH 240050 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 850 PM EDT Fri Mar 23 2018 .SYNOPSIS...
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A frontal zone and related fast-moving wave of low pressure will develop eastward across the southern Appalachians and SC Saturday and Saturday night. Chilly high pressure will otherwise ridge across the southern middle Atlantic states through early next week.
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&& .NEAR TERM /THROUGH TONIGHT/... As of 215 PM Friday... Quiet day weather wise across central NC as surface high pressure over the Gulf Coast is keeping skies clear with seasonably cool temperatures over the area. This surface high, coupled with an upper level trough with the axis just offshore are keeping winds northwesterly through the column this afternoon with some gusting to 15 kts possible. Off to the west, a surface low over Missouri will start to bring clouds into the area from the west after 6z Saturday. Precipitation however is expected to hold off until after 12z. Temperatures overnight will drop in to the mid to upper 30s across the southwest Piedmont with lower 30s across the northern Piedmont and Coastal Plain. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 215 PM Friday... As a low pressure system moves in from the west, chances for winter precipitation are increasing across the VA border counties and areas northwest of I-85. There is very high confidence in a wet weekend with all portions of the forecast area expecting as much as an inch of rain in places. The northern coastal plain may fall short of this number, closer to a half of an inch. This will occur beginning around or just after 12z in the Triad and then pushing eastward across the CWA by 18Z. From this time onward expect precipitation to be occurring until at least 18z Sunday if not a little longer. Latest model guidance does not give much clarity as to the type of winter P-type that may fall in areas north of US-64 this weekend. The event may begin as some brief snow on Saturday morning in the Triad before turning over to all rain for much of the day. The best chance for any accumulating snow will be in the northern portions of the Triad and VA border counties, similar to last event. The favored window for timing will be after 00Z Sunday through 15Z Sunday. Forecast soundings indicate a few hours of very good omega coupled with a saturated dendritic growth zone but that saturated area comes and goes over the course of the evening leaving lots of uncertainty as whether or not precip will be falling as snow or sleet. Nomograms aren`t much help as they also indicate more of a wintry mix through much of the event. There is the chance however for some bursts of heavy snow that could lead to some accumulation on the ground Sunday morning. At this time the forecast calls for as much as an inch of snow accumulation in the northern portions of the VA border and Triad counties with a half an inch or less through much of the I-85 corridor. Further south to US-64 expect a mix of snow and sleet with little to no accumulation and no impacts to travel. In fact, there will likely be no impacts to travel except maybe for some slushy areas in the northern portions of those VA border and Triad counties. Temperatures for the weekend will be cold, with highs Saturday and Sunday likely in the low to mid 40s with some southern locales squeaking out 50 degrees. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 200 PM Friday... Dry and cool weather is expected during the first part of the work week. A few low clouds may hang on through Mon morning in the western CWA as the semi-anchored surface high, centered over SW Quebec into the Maritimes, ridges SSW through NC, generating a weak wedge air mass over central NC. Nocturnal stabilization and a local increase in shallow moist upglide may result in patchy drizzle over the W Piedmont Mon night. Mid level ridging will steadily build over the East Coast through mid week, between deep closed lows over the Desert Southwest and over the NW Atlantic, ensuring a lack of forcing for ascent and continued tranquil weather (albeit with periodic cloudiness, particularly with SW-to-NE passage of a warm frontal zone aloft through the region). The GFS/ECMWF weaken the Desert Southwest low and track it eastward into the Southern Plains by Thu, which nudges the ridge axis offshore and leads to increasing moist SW flow into the area, prompting a rising chance for showers late in the week. This is supported by the GEFS and EPS, although both the ECMWF and EPS lag a bit, closer to the slow Canadian solution. Will opt for the ECMWF`s compromise but slower solution, introducing low shower chances Thu with slightly better chances Fri, but still just near climatology. Surface temps will continue to modify through the week, with soaring 850 mb temps, supporting a trend of highs from the upper 40s to upper 50s Mon to the upper 60s to mid 70s by Fri. -GIH && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
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As of 845 PM Friday... VFR conditions through Sat morning will yield to steadily lowering ones through MVFR-IFR range, along with the eastward development of a shield of precipitation, from west to east between 14Z Sat and 00Z Sun. That precipitation will likely include periods of predominately snow at INT and GSO, and at at least a brief mix at RDU and RWI, as an area of low pressure develops and tracks east across SC. Outlook: While precipitation is expected to end from west to east by Sun morning, periods of MVFR to low VFR ceilings will linger, in residually moist nely low level flow, until drier air advects south into cntl NC by late Sun. IFR ceilings may redevelop late Sun night- early Mon, with VFR conditions otherwise expected through the middle of the week.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...Ellis SHORT TERM...Ellis LONG TERM...Hartfield AVIATION...MWS is the U.S. government's official web portal to all federal, state and local government web resources and services.